In recent years, spatial sound provision has become increasingly popular such as, e.g., evidenced by the wide popularity of various surround sounds systems. For example, the increased popularity of home cinema systems has resulted in surround sound systems being common in many private homes. However, a problem with conventional surround sound systems is that they require a high number of separate speakers located at specific positions.
For example, a conventional Dolby 5.1 surround sound system requires right and left rear speakers, as well front center, right and left speakers. In addition, a low frequency subwoofer may be used.
The high number of speakers not only increases cost but also results in reduced practicality and increased inconvenience to users. In particular, it is generally considered a disadvantage that loudspeakers at specific positions in front as well as to the rear of listeners are needed. The rear loudspeakers are particularly problematic due to the required wiring and the physical impact they impose on the interior of the room.
In order to mitigate this problem, research has been undertaken in order to generate speaker sets that are suitable for reproducing or emulating surround sound systems but use a reduced number of speaker positions. Such speaker sets use directional sound radiation to direct sounds in directions that will result in them reaching the user via reflections from objects in the sound environment. For example, audio signals can be directed so that they will reach the listener via reflections of sidewalls thereby providing an impression to the listener that the sound originates to the side (or even behind) the listener.
However, such approaches of providing virtual sound sources tend to be less robust than real sources positioned to the rear of the listener, and tend to provide reduced audio quality and a reduced spatial experience. Indeed, it is often difficult to accurately direct audio signals to provide the desired reflections that achieve the desired virtual sound source position. Furthermore, the audio signals intended to be received from the back of the listener also tend to reach the listener via direct paths or alternative unintended paths thereby degrading the spatial experience.
Indeed, it has been identified that one of the highest preferences of consumers of, e.g., home cinema and surround systems is that of obtaining a convincing surround experience with as few and small loudspeaker units as possible. Preferably, consumers would like to be able to have a great immersive experience using only a single compact system. In order to address such preferences, loudspeaker arrangements have been developed where a plurality of spatial channels can be generated from a single loudspeaker box. This is typically achieved by the loudspeaker box comprising a plurality of speaker drivers that are individually driven with different weights for each speaker driver. This allows directional audio beams to be formed and may, e.g., be used to direct surround sound channels towards the side so that they will reach the listening position from the side or back due to reflections of walls.
However, although such approaches are often able to create a pleasant wide, spacious sound experience, they do tend to be suboptimal in providing a spatial surround sound experience. For example, they tend to be dependent on the specific audio environment and, e.g., the presence of suitable walls off of which to reflect sound. As a consequence, such systems may, in some scenarios, tend to not provide an accurate and highly realistic impression of sound reaching the listener from behind.
Therefore, it is generally the case that in order to obtain an optimal spatial user experience, the use of loudspeakers located to the side or rear of the user is typically desired. However, whereas improved performance may often be achieved by positioning of surround speakers, e.g., to the side or behind the listening position, such speakers tend to be considered undesirable. Therefore, it is desired that speakers of, e.g., a surround sound system are as small as possible and this has, for example, led to the typical arrangement of relatively small spatial (satellite) speakers combined with a single subwoofer. However, such an approach tends to not provide optimal sound quality. In addition, the spatial experience tends to be degraded as the presence of the subwoofer tends to obscure or confuse the spatial cues perceived by the listener. Furthermore, in order to provide a reasonable sound quality and spatial experience, the cross-over frequency between the subwoofer and the spatial speakers must be kept relatively low. This results in the spatial speakers needing to be of a certain size in order to provide acceptable audio quality and sound pressure towards the lower frequencies.
Hence, an improved speaker system would be advantageous and, in particular, a system that will allow facilitated implementation, facilitated setup, a reduced number and/or size of speakers, an improved spatial experience, improved audio quality and/or improved performance would be advantageous.